Protestors and riot police clashed for a second day in Istanbul on Saturday, a day after an environmental protest flared into a massive outcry against Turkey’s government.

The unrest, which has spread to other cities, marks one of the biggest protests since Prime Minister Recep Tayyip Erdogan first came to power in 2002 and has exposed growing discontent with what critics say is his government’s increasingly conservative and authoritarian agenda.

On Saturday police fired tear gas at protestors gathering in Taksim Square, the epicentre of the demonstrations that have left dozens of people injured and have earned Turkey a rare rebuke from its ally Washington.

Hours earlier, several hundred protestors waving Turkish flags advanced despite police firing water canon and crossed the Bosphorus Bridge to the European side of the city, according to local media.

The unrest erupted into anti-government demonstrations after police on Friday moved into Taksim to break up a protest against the razing of a nearby park.

Clashes raged during the night, as thousands of people marched through the city, some banging pots and pans as residents shouted support from the windows.

Others held up cans of beer in defiance of a recent law, supported by the ruling Justice and Development Party (AKP), which restricts the sale of alcohol and prohibits it during the nighttime hours.

The unrest on Taksim Square, where a sit-in has been held for several weeks to protest against plans to raze a nearby park in order to build a shopping mall.

Critics say that the park is the last patch of greenery in the commercial area.

Its razing is part of a wider, controversial construction project that aims to turn the area around Taksim — a traditional gathering point for protests and a popular tourist destination — into a pedestrian zone.

After several days of growing protests at the square last week, riot police moved in to break it up on Friday with tear gas and water canon.

“The trees, it’s the drop that made the vase overflow,” said Ozkan, a philosophy student in Istanbul. “People are sick and tired of everything that this government is doing to them.”

As tear gas blanketed the area, thousands of people poured out into the streets in support of the demonstrators in other Turkish cities, including in the capital Ankara, the western cities of Izmir and Mugla and Antalya in the south.

Authorities said that a dozen people were being treated in hospitals for injuries received in the clashes, but Amnesty International said more than 100 protesters were reportedly injured.

More than 60 people have been detained as a result of the unrest, according to regional authorities.

In Washington, the State Department said it was concerned about the number of people injured as a result of the protests.

“We believe that Turkey’s long-term stability, security and prosperity is best guaranteed by upholding the fundamental freedoms of expression, assembly and association, which is what it seems these individuals were doing,” US State Department spokeswoman Jennifer Psaki said.

Thousands have voiced support for the protesters on social media in recent days, while Amnesty International urged Turkey to “halt brutal police repression” and investigate abuse claims.